DE102018102466B4 - Seat belt retractor, vehicle seat and motor vehicle - Google Patents

Abstract

Belt retractor (20) for installation in the backrest of a vehicle seat with: - a frame (22), - a belt shaft (24) rotatably mounted in the frame (22), on which a belt (26) is partially rolled up, - an electric motor ( 28) having tensioning device, by means of which the belt shaft (24) can be driven in the winding-up direction, - a blocking device for blocking the belt shaft (24) in the frame (22), the blocking device having a movable locking element (34) which is electrically or electromagnetically working actuator can be acted upon directly or indirectly, - an electronic control unit attached to the frame (22) for the tensioning device and for the blocking device, which has an input interface for the CAN system of the motor vehicle and data from the CAN system for controlling the electric motor (28) of the belt tensioner and the control of the actuator are taken into account, with the electronic control unit has an additional electronic sensor (42) for determining acceleration values and the electronic control unit controls the actuator based on the values measured by the additional electronic sensor (42).

Description

The invention relates to a belt retractor according to the preamble of claim 1, a vehicle seat with such a belt retractor according to claim 8 and a motor vehicle with such a vehicle seat according to claim 9.

Seat belt systems are the oldest passive safety devices in motor vehicle construction and still belong to the core of the safety system of every motor vehicle. Such a seat belt system always has a belt retractor with a belt shaft rotatably mounted in a frame, on which a belt is partially rolled up. The belt has a belt tongue which can be inserted into a belt lock. In most cases, the belt retractor is directly or indirectly connected to the vehicle body, that is, its position relative to the vehicle body cannot be changed. However, it is also known to arrange the belt retractor within the backrest of a vehicle seat.

Many modern belt retractors have a tensioning device with an electric motor, by means of which the belt shaft can be driven in the winding-up direction in order to eliminate any belt slack after detection of a possibly impending impact or also after a detected movement of the vehicle occupant.

A decisive feature of every belt retractor is that it has at least one blocking device, which causes the belt shaft to be blocked in the frame if necessary (i.e. if an accident occurs) so that the belt is no longer - or, if necessary, only against the Force of a belt force limiter - can be pulled out. As a rule, two independent blocking devices are provided (which is also required by law in most countries). These two blocking devices are the so-called belt-sensitive blocking device and the so-called vehicle-sensitive blocking device. The belt-sensitive locking device blocks the belt shaft against the frame when the speed of rotation of the belt shaft exceeds a predetermined value (i.e. when the belt is pulled out too quickly). The blocking device, which is usually more important, is the so-called vehicle-sensitive blocking device, which blocks the belt shaft against the frame when it detects an acceleration exceeding a limit value or a tilting of the vehicle that exceeds a limit value. The vehicle-sensitive blocking device always has a sensor and a blocking element, controlled directly or indirectly by this sensor, of a blocking device acting between the frame and the belt shaft.

Even today, most of the sensors of such a vehicle-sensitive blocking device still work purely mechanically, the operating principle being the inertia-related or gravitation-related deflection of a mass element. This operating principle will now be briefly described using a construction principle that is frequently used: A mass ball is located at the lowest point of a shell. This shell is connected to the vehicle. If the vehicle (and with it the shell) is strongly accelerated or braked, the ball changes its position relative to the shell, and with a defined deflection it moves a lever that triggers the blocking. The same thing happens when the vehicle tips over - in this case, too, the position of the ball changes in relation to the shell, which leads to a lever being actuated by the ball. The same operating principle can also be implemented in the form of a so-called “standing man” construction. This sensor cannot "see" whether the displacement of the ball (or another ingot element) in relation to the shell is due to an acceleration / deceleration or a tilting of the vehicle, since the reaction (the position of the ball relative to the shell changes) is the same. This indistinguishability results physically from the equivalence of heavy and inert mass. This sensor thus ideally detects the two states in which it is intended to cause the belt to lock.

Such mechanical vehicle-sensitive sensors work very well and have the advantage that they - and thus also the belt retractors equipped with them - function completely independently. This self-sufficient functioning is essential, since the highest demands are placed on the reliability of the vehicle-sensitive locking of the belt shaft. Such mechanically operating vehicle-sensitive sensors are particularly suitable for belt retractors which are directly connected to the vehicle body, since their installation position relative to the motor vehicle is precisely known and does not change either. However, systems have also become known in which belt retractors with mechanically operating vehicle-sensitive sensors are accommodated in the backrest of a motor vehicle seat. In this case, however, a mechanically complex readjustment device is necessary so that an adjustment of the angle of the backrest can be compensated for.

For example from the DE 103 51 403 B4 a belt retractor with a vehicle-sensitive blocking device is known, in which the mechanical sensor can be spaced from the frame of the belt retractor, the signal transmission between the mechanical sensor and the blocking device taking place electrically. The locking device has a Electromagnet, by means of which the locking element of the locking device can be moved.

From the DE 199 57 814 A1 it is known to use the data from the vehicle's CAN system to control the electric motor of the tensioning device of a belt retractor. The also describes something similar DE 100 44 426 A1 .

the DE 10 2007 017 669 A1 suggests activating the blocking device of a belt retractor by means of a signal derived from the brake pressure gradient.

From the DE 10 2015 007 555 A1 a device for determining the angle of rotation of a belt reel is known.

Based on this, the present invention sets itself the task of providing a belt retractor for installation in a motor vehicle, in particular for installation in the backrest of a seat of a motor vehicle, which can be produced with little effort and which offers high operational reliability.

This object is achieved by a belt retractor with the features of claim 1. A vehicle seat with such a belt retractor is specified in claim 8, and a motor vehicle with such a vehicle seat is specified in claim 9.

As already mentioned, many belt retractors nowadays have a tensioning device with an electric motor. There is an electronic control device for this electric motor, which is also part of the belt retractor itself. This means that the belt retractor has a frame, a belt shaft rotatably mounted in the frame, an electric motor connected to the frame, which is connected to the belt shaft directly or via a gear, an electronic control unit attached to the frame for this electric motor and a blocking device for vehicle-sensitive blocking the belt shaft. Here, the blocking device always has a sensor and a blocking device controlled by the sensor, which has a movable blocking element.

The basic idea of the invention now consists in designing the electronic control unit which is already present with an additional electronic sensor which serves as a sensor for the vehicle-sensitive blocking device. Such a sensor can be designed as a separate component or integrated in an integrated circuit (IC). Such sensors are widespread in today's electronic devices, such as cell phones and tablets, and generally detect both acceleration values and a tilting of the sensor with respect to a target position. Thus, if they work two-dimensionally, such sensors do exactly what a mechanical sensor of a vehicle-sensitive blocking device does. So you can replace one. In the event that a blocking device with such a two-dimensional working sensor were installed fixed to the body, it would not require any further information (like a mechanical sensor described above) and could therefore work completely independently. According to the invention, however, such a blocking device is installed in the backrest of a vehicle seat, and therefore it requires additional information (namely from the CAN system of the vehicle) in order to mathematically compensate for a pivoting of the backrest. In this case, it is a semi-autonomous system, but the actual “blocking” information is generated autonomously in the belt retractor and is therefore sufficiently fast and safe.

However, there are also three-dimensional sensors whose additional sensor axis (Z-axis) can be used, whereby a completely self-sufficient vehicle-sensitive blocking device can be formed.

However, there are other advantages to using an electronic sensor (IC sensor). Mechanical sensors have exactly one switching point. IC sensors continuously provide data. This creates the option of adapting locking scenarios. For example, the locking can take place on the basis of acceleration profiles, not on the basis of a fixed threshold value, which results in optimized locking behavior, for example, when driving off-road, fast cornering and roll-over scenarios.

Preferred embodiments of the invention emerge from the subclaims.

• 1 eine schematische Darstellung eines Fahrzeugsitzes mit einem Gurtaufroller,
• 2 den Fahrzeugsitz der 1, wobei die Rückenlehne des Fahrzeugsitzes gegenüber dem Zustand der 1 verschwenkt ist,
• 3 den in den 1 und 2 gezeigten Gurtaufroller in einer vergrößerten und ebenfalls stark schematischen Ansicht,
• 4 einen Beschleunigungssensor, welcher Teil der elektronischen Steuerungseinheit des Gurtaufrollers der 3 ist,
• 5 ein Blockschema der Funktionsweise der Blockiereinrichtung des Gurtaufrollers der 3,
• 6 eine alternative Ausführungsform eines Gurtaufrollers in einer der 3 entsprechenden Darstellung,
• 7 den Beschleunigungssensor des Gurtaufrollers der 6 und
• 8 ein Blockdiagramm der Funktionsweise des Gurtaufrollers der 6.

The invention will now be explained in more detail on the basis of exemplary embodiments with reference to the figures. Here show:

• 1 a schematic representation of a vehicle seat with a belt retractor,
• 2 the vehicle seat of the 1 , the backrest of the vehicle seat compared to the state of 1 is pivoted
• 3 the in the 1 and 2 Belt retractor shown in an enlarged and also very schematic view,
• 4th an acceleration sensor, which is part of the electronic control unit of the belt retractor 3 is,
• 5 a block diagram of the functioning of the blocking device of the belt retractor 3 ,
• 6th an alternative embodiment of a belt retractor in one of the 3 corresponding representation,
• 7th the acceleration sensor of the belt retractor of the 6th and
• 8th a block diagram of the functioning of the belt retractor of 6th .

the 1 and 2 show a schematic representation of a vehicle seat 10 . This can be any individual seat of a vehicle, that is to say in particular the driver's seat or the front passenger seat, but also an individual seat in the rear of a vehicle. In such a vehicle seat, the backrest 14th opposite the seat 12th be pivoted. Adjustment is usually done electrically, but it can also be done manually. In the backrest 14th is a seat belt retractor 20th arranged, which below with reference to the 3 is described in more detail.

It is to be said in advance that the 3 is very schematic and the specific mechanical structure of such a belt retractor can differ greatly from this schematic representation. For the present invention, however, it is not the specific mechanical structure that is important, but the interaction of the individual elements.

The belt retractor 20th has a frame 22nd made of a rigid material, such as sheet steel in particular. This frame 22nd carries all the elements described below: Rotatable on the frame 22nd is a belt shaft 24 held on which a strap 26th is partially wound up. It's one between frames 22nd and belt shaft 24 acting belt-sensitive blocking device is provided, but this is not shown. The belt retractor also has a reversible tensioning device with an electric motor 28 . This is direct or, as shown, via a gearbox 30th with the belt shaft 24 connected. To control this motor 28 an electronic control unit is used, which is also attached to the frame. Schematically shown in 3 the circuit board 40 this electronic control unit (and also very schematically) various electronic components that are on this circuit board 40 are arranged. The electronic control unit is connected to the vehicle electrical system; this is indicated by the arrow with the reference number 50 indicated.

As already mentioned, one of the tasks of the electronic control unit is the electric motor 28 to drive the tightening device, including a supply line 52 serves. A data line could also be provided via which the electric motor 28 Reports status data back to the control unit (not shown).

According to the invention, however, the electronic control unit has a second task, namely it is part of the vehicle-sensitive blocking device, namely it carries its sensor 42 . This sensor can be a separate component or it can be part of an integrated sound circuit (IC). The other part of the vehicle-sensitive blocking device is the mechanical blocking device, which is characterized in that it has an actuator controlled by the electronic control unit, an electromagnet in the exemplary embodiment shown 32 , having. The control of the electromagnet 32 by the electronic control unit takes place via the supply line 54 . The actuator (here the electromagnet) interacts with a mechanical locking element. The action of the electromagnet can (as shown) take place either directly or indirectly (for example by actuating a lever). In this respect, the representation in 6th to be understood only as schematic and exemplary. In the embodiment shown, acts between the locking element 34 and the frame 22nd a feather 36 . Is the electromagnet 32 switched on ie that current through the supply line 52 flows, the electromagnet pulls 32 the locking element from a locking head 24a the belt shaft 24 away and the belt shaft can move in the frame 22nd rotate. No current flows through the supply line 54 the locking element moves into the locking head and the belt shaft due to the force of the spring 24 is against the frame 22nd blocked. If, in the event of an accident, the power fails completely, the locking status occurs automatically (fail safe).

In the first embodiment, the sensor is 42 a three-axis sensor, ie it registers a rotation and an acceleration in all three axes X (vehicle longitudinal axis), Y (vehicle transverse axis) and Z (vertical axis) - see 4th . As a result, the system can basically work completely independently (except for the power supply), as follows (partly with reference to the 5 ) is described in more detail.

• Werkseitig ist die Lage des Sensors 42 in Bezug auf das Kraftfahrzeug bekannt. Dies kann insbesondere dadurch geschehen, dass die Einbaulage des Sensors in Bezug auf die Rückenlehne bekannt ist und dass die Ausgangsposition der Rückenlehne (d.h. ihre Ausgangsneigung in Bezug auf das Kraftfahrzeug) bekannt ist. Somit kennt die elektronische Steuerungseinheit die echte X-Achse, die echte Y- Achse und die echte Z-Achse. Hiervon ausgehend werden die Änderungen der Messwerte in X-, Y- und Z-Richtung fortlaufend überprüft und hiervon ausgehend entschieden, ob ein Zustand vorliegt, in welchen die Gurtwelle blockiert wird. Dies erfolgt beispielsweise nach folgendem Schema: Wird die Rückenlehne verstellt (d.h. sie wird um eine Achse verschwenkt, welche parallel zur Y-Achse ist), so ändern sich die Messwerte sowohl in X- als auch in Z-Richtung und dies aufgrund der Langsamkeit der Verstellung auch nur relativ langsam. Dasselbe passiert, wenn das Fahrzeug eine Steigung oder ein Gefälle befährt. In diesem Fall erkennt die elektronische Steuerungseinheit diese Änderung und berechnet dann durch eine Koordinatentransformation die Referenz (d.h. die X-Y-Ebene) neu. Es erfolgt dann keine Blockierung der Gurtwelle und das System legt die neu berechnete Referenzebene zugrunde. Somit ist die „echte“ X-Y-Ebene fortlaufend bekannt. Unter „echter“ X-Y-Ebene wird hierbei die X-Y-Ebene verstanden, welche parallel zur gravitativen Horizontalebene ist. Beschleunigt ober bremst das Fahrzeug jedoch, so ändert sich der Messwert nur in X-Richtung, nicht in Z-Richtung. Die elektronische Steuerungseinheit kann somit (dies kann ein mechanischer Sensor nicht) zwischen Rückenlehnenverstellung und Beschleunigung (positiver oder negativer) unterscheiden und führt somit bei detektierter Beschleunigung keine Anpassung der X-Y-Ebene durch.

The task of the vehicle-sensitive blocking device is to block the belt shaft against the frame when the acceleration values (positive or negative acceleration values) of the motor vehicle - especially in the X direction) exceed a predetermined value, or when the vehicle is tilted by the X or the Y-axis exceeds a predetermined value. The belt shaft must not be blocked during all other changes in status, especially when driving up an incline, adjusting the backrest or "normal" acceleration and braking. the The blocking device according to the invention solves this problem as follows:

• The position of the sensor is factory-set 42 known in relation to the motor vehicle. This can take place in particular in that the installation position of the sensor in relation to the backrest is known and in that the starting position of the backrest (ie its starting inclination in relation to the motor vehicle) is known. Thus the electronic control unit knows the real X-axis, the real Y-axis and the real Z-axis. Based on this, the changes in the measured values in the X, Y and Z directions are continuously checked and, based on this, a decision is made as to whether there is a state in which the belt shaft is blocked. This is done, for example, according to the following scheme: If the backrest is adjusted (i.e. it is pivoted about an axis which is parallel to the Y-axis), the measured values change in both the X and Z directions and this is due to the slowness of the Adjustment only relatively slowly. The same thing happens when the vehicle drives up or down a slope. In this case, the electronic control unit recognizes this change and then recalculates the reference (ie the XY plane) by means of a coordinate transformation. The belt shaft is then not blocked and the system uses the newly calculated reference plane as a basis. This means that the “real” XY plane is continuously known. The “real” XY plane is understood here to be the XY plane, which is parallel to the gravitational horizontal plane. However, if the vehicle accelerates or brakes, the measured value only changes in the X direction, not in the Z direction. The electronic control unit can thus (a mechanical sensor cannot) differentiate between backrest adjustment and acceleration (positive or negative) and therefore does not carry out any adaptation of the XY plane when acceleration is detected.

If, on the other hand, the motor vehicle is accelerated very strongly in the X direction (rear impact) or braked (frontal impact), the measured value in the X direction changes very strongly in a short time. This allows the control unit to clearly calculate the "accident" state so that a blockage occurs. If the car tips over, the measured values in the Y and Z directions change above a predetermined limit value, which is also interpreted as an accident and leads to the belt shaft locking. A rotation around the Y axis (change in the measured values in the X and Z directions) which exceeds a certain limit value can also be interpreted as an accident. So you can see that the system can work completely independently. It does not require any information from outside the belt retractor, which means that the necessary reaction speed can be achieved. The additionally generated information can be sent via a data output 62 to the vehicle's CAN system.

In the second embodiment ( 6th until 8th ) is the sensor 42 just a 2-axis sensor. Compared to the first exemplary embodiment, there is no measurement in the Z direction. This is compensated for by the fact that the control unit has a data input (reference number 60 in 6th ) for connection to the CAN system of the motor vehicle. With the aid of this data, the real XY plane can be continuously calculated by the control unit, especially when the backrest is adjusted. The relatively low speed of the CAN system is sufficient for this. In the event of abrupt changes in the X or Y values, however, the belt retractor reacts autonomously and blocks the belt shaft. If such a belt retractor is rigidly connected to the body (i.e. not mounted in a backrest), it can work completely autonomously even if it only has a 2-axis sensor.

Providing a connection to the CAN system can, however, also be useful if the belt retractor has a 3-axis sensor, as this results in numerous other advantages: A redundant comparison of sensor data is possible, which increases the functional Security leads. The vehicle's wake-up strategy can also be used, which improves power management. Despite the fail safe (no electricity - no belt), a friction brake can be omitted, as modern vehicles switch to limp mode in the event of a breakdown, for example. The ability to diagnose and query the status of the interlocking function is improved, which increases functional safety. The seat position can be adjusted to the vehicle inclination, e.g. to be able to buckle up in a vehicle parked on a mountain (increased comfort). Finally, the seat position detection (i.e. the detection of the inclination of the backrest) (HAD mode) can be reported back to the vehicle (to select the active safety strategy).

As shown in both exemplary embodiments, a belt shaft sensor 25th be provided. By integrating this data into the locking algorithm, there are further advantages: On the one hand, by using this information, the pre-tensioning behavior can be coordinated more elegantly and finely, which further increases the wearing comfort and convenience of use. This is particularly important for any HAD modes that, in addition to partially / autonomous driving, require precisely the comfort aspect. Furthermore, locking, in particular on a shaking section, can be avoided in this way if no belt pull-out is detected. In addition, "accidental" locking when buckling up quickly can be suppressed. Finally, a child seat function can be achieved without mechanical implementation.

List of reference symbols

10

Vehicle seat

12th

Seat

14th

backrest

16

headrest

20th

Belt retractor

22nd

frame

24

Belt shaft

24a

Locking head

25th

Belt shaft sensor

26th

belt

28

Electric motor

30th

transmission

32

Electromagnet

34

Locking element

36

feather

40

Circuit board

42

Accelerometer

50

Power supply

52

Electric motor supply line

54

Supply line of the electromagnet

60

Data input

62

Data output

Claims (9)

Belt retractor (20) for installation in the backrest of a vehicle seat with: - a frame (22), - A belt shaft (24) rotatably mounted in the frame (22), on which a belt (26) is partially rolled up, - A tensioning device having an electric motor (28), by means of which the belt shaft (24) can be driven in the winding direction, - a blocking device for blocking the belt shaft (24) in the frame (22), the blocking device having a movable blocking element (34) which can be acted upon directly or indirectly by means of an electrically or electromagnetically operating actuator, - An electronic control unit attached to the frame (22) for the tensioning device and for the blocking device, which has an input interface for the CAN system of the motor vehicle and data of the CAN system for the control of the electric motor (28) of the belt tensioner and the control of the actuator taken into account, where - The electronic control unit has an additional electronic sensor (42) for determining acceleration values and - The electronic control unit controls the actuator based on the values measured by the additional electronic sensor (42). Belt retractor Claim 1 , characterized in that the actuator is an electrically switchable magnet (32). Belt retractor according to one of the preceding claims, characterized in that the blocking element (34) blocks when the actuator is de-energized. Belt retractor according to one of the preceding claims, characterized in that it furthermore has a belt shaft sensor (25) which detects the rotation of the belt shaft (24) with respect to the frame (22), and that the control unit detects the values of the belt shaft sensor (24) and the Adjusts the values of the electronic sensor (42). Belt retractor according to one of the preceding claims, characterized in that the electrical sensor (42) is a 3-axis sensor. Belt retractor according to one of the Claims 1 until 4th , characterized in that the electronic sensor (42) is a 2-axis sensor. Belt retractor according to one of the preceding claims, characterized in that the control unit has an output interface for the vehicle ECU, so that it provides it with data from the belt shaft sensor and / or data from the additional sensor. Vehicle seat (10) in its backrest (14) has a belt retractor (20) according to one of the Claims 1 until 7th is built in. Motor vehicle with a vehicle seat (10) according to Claim 8 .

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